Method of forming an improved hydrophilic coating on a polymer surface

Abstract

A method of forming an improved hydrophilic coating by applying on a non-reactive hydrophilic polymer surface layer an osmolality-increasing compound to produce a more stable hydrophilic surface and to produce a more slippery surface in wet condition. The polymer surface layer is treated with a solution having above 2% (weight/volume) of an osmolality increasing compound and then the solvent of the solution is evaporated. Osmolality increasing compounds are nontoxic organic or unorganic salts other than trihalogenids, mono- or di- saccharides or sugar alcohols. Preferred compounds are glucose, sorbitol, sodium chloride, sodium citrate, sodium bensoate, calcium chloride, potassium chloride, potassium iodide, potassium nitrate. The solution of the osmolality increasing compound contains preferably a polymer. Medical articles treated with the solution of osmolality increasing compounds according to the method above also relate to the invention.

We claim: 
     
       1. A method of forming an improved hydrophilic coating on a substrate, comprising: (a) applying a non-reactive hydrophilic polymer layer to the substrate;   (b) applying to the non-reactive hydrophilic polymer layer a solution comprising a solvent and at least 2% (weight per volume) of an osmolality-increasing compound selected from the group consisting of mono and disaccharides, sugar alcohols, and non-toxic organic and inorganic salts, with the proviso that the osmolality-increasing compound is not a trihalogenide; and   (c) evaporating the solvent.   
     
     
       2. A method according to claim 1 wherein the osmolality-increasing compounds is selected from the group consisting of glucose, sorbitol, sodium chloride, sodium citrate, sodium benzoate, calcium chloride, potassium chloride, potassium iodide and potassium nitrate. 
     
     
       3. A method according to claim 1, wherein the osmolality-increasing compound is selected from the group consisting of glucose, sodium chloride, sodium citrate, sodium benzoate, calcium chloride, potassium chloride, potassium iodide and potassium nitrate. 
     
     
       4. A method according to claim 1, wherein the solution further comprises a polymer. 
     
     
       5. A method according to claim 1, wherein the solution contains about 4% to about 40% (weight to volume) of sodium chloride. 
     
     
       6. A method according to claim 1, further comprising the step of curing the polymer layer prior to treatment with the osmolality-increasing agent. 
     
     
       7. A method according to claim 1, wherein the polymer layer comprises a polymer selected from the group consisting of polyethuleneoxide, polyvinylpyrrolidone, polyvinyl compounds, polysaccharides, polyurethanes, polyacrylates and copolymers thereof. 
     
     
       8. A method according to claim 1, wherein the polymer layer comprises polyvinylpryyolidone, and the solution comprises 20% (weight/volume) sodium chloride. 
     
     
       9. A method according to claim 4, wherein the polymer contained in the solution is the same polymer as is used in the non-reactive hydrophilic polymer surface layer. 
     
     
       10. A method according to claim 1, wherein the osmolality-increasing compound is selected from the group consisting of glucose and sorbitol. 
     
     
       11. A method according to claim 10, wherein the osmolality-increasing compound is selected from the group consisting of glucose and sorbitol. 
     
     
       12. A method according to claim 1, wherein the osmolality-increasing compound is selected from the group consisting of sodium chloride, potassium chloride, calcium chloride, potassium iodide and potassium nitrate. 
     
     
       13. A medical article according to claim 1, wherein the osmolality-increasing compound is selected from the group consisting of sodium chloride, potassium chloride, calcium chloride, potassium iodide and potassium nitrate. 
     
     
       14. A medical article having a very low coefficient of friction when wetted with a water-based liquid comprising: (a) substrate,   (b) a non-reactive hydrophilic polymer layer disposed on the surface of said substrate; and   (c) an evaporated hydrophilic coating disposed on the polymer layer, said evaporated hydrophilic coating comprising an osmolality-increasing compound selected from the group consisting of non-toxic organic and inorganic salts, mono- and disaccharides, and sugar alcohols, with the proviso that the osmolality-increasing agent is not a trihalogenide.   
     
     
       15. A medical article according to claim 14, wherein the osmolality-increasing compound is selected from the group consisting of glucose, sorbitol, sodium chloride, sodium citrate, sodium benzoate, calcium chloride, potassium chloride, potassium iodide, and potassium nitrate. 
     
     
       16. A medical article according to claim 14, wherein osmolality-increasing compound is selected from the group consisting of glucose, sodium chloride, sodium citrate, sodium benzoate, calcium chloride, potassium chloride, potassium iodide, and potassium nitrate. 
     
     
       17. A medical article according to claim 14 which is catheter. 
     
     
       18. A medical article according to claim 17 which is a urinary catheter. 
     
     
       19. A medical article according to claim 14, wherein the osmolality-increasing compound is selected from the group consisting of mono- and disaccharides and sugar alcohols. 
     
     
       20. A medical article according to claim 19, wherein the osmolality-increasing compound is selected from the group consisting of glucose and sorbitol.